Apparatus for pulverizing and feeding fuel to furnaces



Jan. 5 1926.

, L. H. BERGMAN APPARATUS FOR PULVERIZING AND FEEDING FUEL TO FURNACESFiled April 17, 1924 3 Sheets-Sheet 1 Jan. 5 1926.

L. H. BERGMAN APPARATUS FOR PULVERIZING AND FEEDING FUEL TO FURNACES 3Sheets-Slheet 2 Filed April 17, 1924 Jan.

L. H. BERGMAN APPARATUS FOR PULVERIZING' AND FEEDING FUEL TO FURNACESFiled April 17, 1924 3 Sheets-Sheet 5 verizing and Feeding Fuel toFurnaces, of

Patented J an. 1926.

UNITED STATES PATENT OFFICE.

LABS H. BERGMAN, OF CHICAGO, ILLINOIS, ASSIGNOB 1'0 RAYMOND BROS.ENGINEER- ING 00., OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

APPARATUS ron runvnnrzme AND FEEDING rum. 'ro r'UnNAcEs.

Application filed April 12, 1924. Serial No. 707,308.

To all whom it may concern:

Be it known that I, LARs H. BERGMAN, a citizen of the United States,residin at Chicago, in V the county of Cook and tate of Illinois, haveinvented certain new and useful Improvements in Apparatus for Pulwhichthe following is a specification.

My invention relates to an apparatus for pulverizing coal and feedingthe same into a furnace, and the invention has for its.

general purpose to provide a new and improved apparatus whereby thecoal, instead of being stored after pulverization and withdrawn from thestorage bin in the quantities required for feeding to the furnace,

is carried directly by an air currentfrom the.

mill to the furnace, the pulverization taking place in the mill beingregulated so as to meet the requirements of the furnace without excess.

The invention contemplates preferably the operation of the mill at aconstant speed and the regulation of output by control of the feed ofthe coal to the mill. With suchv an arrangement in view one of thespecific ob ects of the invention 1s to provide means whereby the airintroduced into the pulverized coal, into the mill for example, is

proportioned in quantity to the fuel so that a proper ratio between airand fuel is maintained regardless of the rate at which the fuel issupplied to the mill.

A further object is to provide for decreasing'the velocity of the fuelstream as it enters the furnace. The transportation of the fuel insuspension necessitates an air current which, if not dampened, will givethe burner flames a higher velocity than is usually de-- sirable. I

A further object is to provide means operative to prevent back firingand explosion in the mill in case movement of fuel from ing out theabove stated objecls and such other-incidental objects as willbereferred to in the following description of there ferred embodiment ofthe invention i ustrated in the drawings.

In the drawings- Fig. 1 is a side elevation with. parts. in section of apulverized coal furnace and the means provided by my invention forpulverizing the coal and feeding the same directly into thefurnace.

Fig. 2 is a vertical sectional view of one of the fuel nozzles andassociated parts.

. Fig. 3 is a cross sectional view on line 33 of Fig. 2.

I I Fig. 4 is a fragmentary plan view of the change speed mechanism forregulating the of Fig. 5, and

Fig. 8 is a fragmentary view, in elevation,

im a... 7-7

of the feed conduit, illustrating the autodevice for preventing backmatic protecting firing into the mill.

Referring first to Fig. 1, A designates a pulverized fuel burningfurnace which may e of any preferred ty e. furnace shown, 10 is te ashpit, 11 the In the. type of boiler tubes, 12 the steam dome and 18 thestack flue. Fuel and air are introduced through'the front wall 14 of thefurnace in a downward direction through a multiple nozzle structure Bconsisting, in the case shown, of three burners.

C is a pulverizin ap aratus which is shown as a roller mil of the Ramond type in which the pulverization of t e material takes place betweena stationary bull ring 15 and a lurality of rollers 16 on pendantjournals 1 supported by a spider 18; on a rotating shaft 19. 4

D is a feeding device of the sort common to mills of this typecomprising a bin 20 and a rotary pocket feeder the shaft 21- of which 'Iisprovided with a ratchet wheel 22. In the installation herein shown theratchet 22 is driven'by a pawl 23,carried by a crank and link mechanism24 provided for oscillating the crank, which link mechanism is operatedfrom a shaft 25. Shaft 25 has a pulley 26 for a belt 27 which extendsaround a pulley 28 driven by suitable gearing 28' from a shaft 29 drivenfrom a variable speed transmission (Fig. 4) to be hereinafter referredto.

E is a conduit leading from the top of mill C to a fan or blower F withthe .educ tion pipe of which nozzle B is connected.

G (Fi 8) is a mechanism interposed between t e fan F and the nozzle Bfor preventing back firing in case the mill stops.

The central shaft 19 of the mill is geared within the mill to a shaft30, driven from an electric motor 31 the armature shaft of which isprovided with a pulley 32 connected by belt 33 with a pulley on shaft30. Shaft has fixed thereto a sprocket 34 connected by chain 35 with thedriving sprocket 36 of a Reeves variable speed transmission, the drivensprocket of which is des gnated 37 and is connected by chain 38 with asprocket on shaft 29, above referred to. The Reeves variable speedtransmission is of familiar construction and need not be described indetail; and, in fact, any other variable speed device of suitableconstruction might be used in place of it. By shifting the ends oflevers 39, 40 of the speed changing device to and from each other by themanipulation of screw 41 the pulleys 42, 42 and 43, 43 are spread apartor brought closer together so as to vary the speed ratio as between thedriving sprocket 36 and the driven sprocket 37, and hence the rate offeed of coal to the mill.

Air enters the circular air drum of the mill, from where it goes to themill under bull ring 15 and rollers 16, througha casin 45 which is openat the top and is provi ed with one or more valves or dampers, theposition of which is controlled from the variable speed transmissionemplo ed for re lating the quantity of coal fe to the infi l In thedrawings (see particularly Figs. 1, 5 and 7) I have shown two dampers46, 47 provided with gudgeons 48, 49, 50 and .51 turning in hearings inthe upper member 52 of casing 45. Gudgeons 49, 51 are provided withlevers'53, 54 connected by a link 55, and, pinned to gudgeon 51, 1s alever 56 to which is secured a weight 57. Lever 56 is connected by atwo-part link 58 provided with a turn buckle 59 with one arm of a bellcrank 60 which is pivoted to the frame 61 of the variable speedtransmission. The lever 40 of the transmission mechanism bears againstthe other, upstanding, arm 62 of hell crank 60. As a result of thisarrangement when the feed of coal to the mill is reduced, that is, whenthe forward ends of levers 39, 40 of the variable speed transmission arespread further apart and the opposite ends brought closer together toslow down the rotation of the revoluble pocket feeder, lever 40 is movedto the right Figs. 4 and 5) and the weight 57 moves ampers 46, 47 towardtheir closing positions. The reverse operation takes place when the feedof fuel to the mill is increased.

Preferably the current of air and fuel is divided and fed into thefurnace through a plurality of nozzle pipes terminating in burners,although the invention contemplates the use of a single nozzle. Themultiple nozzle shown in the drawings comprises three identical pipesections 63 (Fig. 6) having the longitudinal configuration shown in Fig.2. Projecting into and extending through each of the pipe sections 63 isa tubular member 64 open at its upper end to the atmosphere and at itslower end to the furnace. The nozzle or burner extends through the frontwall of the furnace as shown in Figs. 1 and 2. The tubular member 64provides a core of induced or auxiliary air in the middle of the streamof primary air and fuel. The auxiliary air operates to reduce thevelocity of the fuel stream and of the flame produced thereby. This isparticularly desirable in the direct feeding system with which mypresent invention is concerned since the transportation of thepulverized fuel in suspension from the blower to the furnace involvesthe use of an air current of a higher velocity than is desired at thepoint where the fuel enters the furnace. A high flame velocity is noteconomical of fuel and tends to burn out and slag the boiler setting.

The nozzle pipes 63 are connected with a header casing 65, the lattercommunicating, by the interposition of a conduit section 66, to bedescribed, with the eduction pipe 67 of the fan F. The fan may be of anydesired type and is shown as driven by an electric motor 68. Extendingthrough the header casing are a pair of vertical shafts 69 to which aresecured, within the casing, deflecting vanes 70 and on their upper endsabove the casing a pair of fingers 71 for setting the vanes to anydesired positions within the range of their angular movements. By aproper adjustment of the vanes the single stream of air and fuel fromfan F is divided vertically into the three streams which enter nozzlepipes 63. The division of the stream of fuel and air vertically insuresuniformity in the ratio as between air and fuel in the divided streams.Ordinarily the lower portion of the air stream will carry more of thesolids than the upper portion, hence the desirability of dividing themain stream vertically instead of horizontally.

Extending through the upper portion of the conduit section 66 is'a shaft72 to which is fixed a valve 73 formed so that when in the positionshown in dotted lines in Fig. 8 it will shut off casing 65 from theeduction pipe 67 of the fan. Shaft 72 has fixed to one end thereof,outside of section 66, an arm 74 carrying a weight 75, the arm beingformed with a downturned finger 76. Under normal operating conditionsthe valve 73 is held in the upper part of section 66 by a latch 77 fixedto a rock shaft 78 supported by up-- rights 79 on the 'top of casing 66.Connected rigidly with the rock shaft is an arm 80 connected by a clevis81 to the core 82 of a solenoid 83. A weight 84 is fixed to the outerend of arm 80. The solenoid is connected in parallel, by wires 85 withthe leads 86 of the and might produce a destructive explosion in themill. This possibility is forestalled/ by the apparatus just described.When the fan is stopped by shutting off current to lts driving motor 68,current is simultaneously shut off from solenoid 83 which is deenergizedand drops its core. Weight 84 rocks thecrank structure 80, 78, 77, sothat the latch end of the structure 77 is disengaged from the finger 76of lever 7 4 and the weight 75 causes the lever to drop, thereby movingvalve 73 to its closing position.

a Summary of operation.-'-The feed of coal to the mill C through feederD is controlled by operation of the variable speed transmission (Fig.4). Simultaneously dampers 46, v 47 are shifted, automatically, toincrease or decrease the air supply to the mill. The

coal, when pulverized sufliciently to be raisedby the air lift createdby fan F, is drawn up I through pipe E into the fan and passes from thefan throu h casin 66 and to the multiple burner the single stream beingd1- vided vertically into three streams byvanes 7 0. Auxiliary air isdrawn into each burner nozzle through pipe 64 forming'a central air corewithin the stream of rimary air and fuel which brings about diminutionof the velocity of-the burner flames. stoppa of the fanEvalve 73 isdroppedthrong deenergization of solenoid 83 to prevent back firing intothe mill. Valve 73 may be re-set by hand when the mill is started up.

WhileIhave described my invention in a furnace provided with a centrallyarranged preferred embodiment comprising several features intending tobe used in combination, it is realizedthat some of these features Iwouldhave utility when'usedin other situations. and that it isnotewential that all "of the features shown be combined in a sin leinstallation. As to details ofconstructionand -arrangement,modifications might be made withoutldeparture the principles of theinvention." Therefore intend to r yp nnw l w m 'inthe scope'iofth ed"spen 1. Incombination 'atingjat a a i w ea m In case of l ui med m1 iiiffi r nsz'i.,' op rrli mgp s %ed; m ans*iorintre-* ithrougli saidconduit directly ties, mechanism for introducing air into the mill tocarry out the pulverized .fuel and transport the same to the furnace,and meansfor automatically controlling the int-roduction of air tomaintain .an approximately constant ratio between airand fuel, and aburner for the introduction of the fuel stream into the furnace providedwith a duct through which auxiliary air enters the fur nace with saidfuel stream.

2. In combination with a furnace for burning pulverized fuel, apulverizing mill operating at a constant speed, means for introducingfuel into the mill in variable quantities, mechanism for introducing airinto the mill to carry outAthe pulverized fuel and transport the same.to the furnace, means for automatically controlling the introduction ofair to maintain an approximately constant ratio between air and fuel,and a burner for the introduction of the fuel stream into the furnaceprovided with a duct throughwhich auxiliary air isdrawn into the,furnace with the fuel stream by induction.

3. In combination with a furnace for burning pulverized fuel, apulverizing mill operatfurnace provided with a centrally arranged 1auxiliary air conduit.

4:. .In coinbination'with a furnace for burningpulverized fuel, apulvering mill operatmg at a constant speed, means for introducing fuelinto the mill in variable quantities,

mechanism for introducing air into the mill to carry out the pulverized.fuel and transport the same to the furnace, means for antomaticallycontrolling the introduction of air to maintain an approximatelyconstant ratio between air and fuel, and a burner for the introductionofthe fuel stream into the auxiliary air conduit through which air isdrawn into the furnace by induction.

5. The combination with a furnace for burning pulverized fuel,,a .millfor pulver-- thefuel, a conduit, andmeansfor propolling the fuel in susnsion in an air current through the con uitidirectly from themill to thefurnace; of means operative automatically when, the fuel pro Hing meansis. de-energized for shutting o v communica- 'tion between the furnace.and'themill.

1 6. The combination with a furnace for i i g e a for pu in the" el;iaconduit,gand fol-pros in'g fuelsuspension air-current anemia to thefurnace; of a valve in said conduit, means which normally holds saidvalve in a non-obstructing position, and mechanism actuatedautomatically when the fuel propelling means is de-energized forreleasing the valve so that it falls to a position to closecommunication between the furnace and mi 1.

7. The combination with a. furnace for burning pulverized fuel, a millfor pulverizing said fuel, a conduit through which fuel is carried insuspension in an air current directly from the mill to the furnace,means for propelling the fuel through the conduit, and an electric motorfor driving the propelling means; of mechanism actuated when current isshut off from the motor for closing communication from the furnace tothe mill.

8. The combination with a furnace for burning pulverized fuel, apulverizing mill, a conduit through which fuel is carried in suspensionin an air current directly from the mill to the furnace, means forpropelling the fuel through the conduit, and an electric motor fordriving the propelling means; of a valve adapted to close communicationbetween the furnace and the mill, means to automatically close thevalve, and releasable mechanism comprising an electro-magnet energizedand de-energized when the current is supplied and shut off from themotor for holding said valve in an unobstructing position when the millis operating and for releasing the valve so that the closing means willmove it to closed position when the mlll is stopped.

9. The combination with a furnace for burning pulverized fuel, apulverizing mill, a conduit through which fuel is carried in suspensionin an air current directly from the mill to the furnace, means forpropelling the fuel through the conduit, and an electric motor fordriving the propelling means; of a valve adapted to close communicationbetween the furnace and mill, a solenoid energized and deenergized whencurrent is supplied to or shut off from the motor, a latch connectedwith the solenoid core for supporting said valve in an unobstructingposition when the solenoid is energized, and

means for releasing the valve from said latch when said solenoid isdeenergized.

10. In combination, a furnace for burning pulverized fuel, a pulverizingmill, a conduit and blower for withdrawing air and pulverized fuel fromthe mill and introducing the same into the furnace, an electric motorfor driving said blower, a valve in said conduit provided with a rockshaft, a weighted arm on said rock shaft, a solenoid energized anddeenergized when said motor is supplied with and deprived of currentrespectively, a weighted lever pivoted to the solenoid core providedwith a lever engageable with the arm on said rock shaft when thesolenoid is energized and adapted to be disengaged from said arm whenthe solenoid is deenergized.

11. In combination with a furnace for burning pulverized fuel, a conduitleading to the furnace through which pulverized fuel is transported tothe furnace in sus ension in an air current, a blower to pro uce the aircurrent, means for operating the blower, a valve in said conduitnormally in an unobstructing position, and means whereby when theblower-operating means is deenergized, said valve is automatically movedto a position to close said conduit.

12. The combination of a furnace for burning pulverized fuel, a conduitleading to said furnace, means for transporting pulverized fuel insuspension in an air current through said conduit to the furnace, saidmeans comprising an electric motor, a valve normally held in anunobstructing position and adapted to be released to obstruct thepassageway through said conduit, and means for holding said valve in itsunobstructing positlon comprising an electro-magnet energized anddeenergized when said electric motor is supplied with and deprived ofcurrent, respectively.

13. In combination with a furnace, a conduit leading thereto throughwhich pulverized coal is supplied to the furnace, a valve in saidconduit. a latch for holding said valve in an unobstructing position, asolenoid having a core to which said latch is pivoted, and means wherebywhen the solenoid is deenergized the valve is released from said latch.

14. In combination, a furnace, a pulverizing mill having an air intake,means for feeding fuel in variable quantities into the pulverizing mill,means for controlling the introduction of air into the mill through saidintake proportionately to the introduction of fuel, a conduit leadingfrom the mill to the furnace, a fan in said conduit, means for rotatingthe fan, a valve, nomally in unobstructing position in said conduit andmeans which automatically operate to i cause the valve to move to anobstructing position when the fan-rotatlng means is deenergized.

LABS H. BERGMAN.

Certificate of Correction.

It is hereby certified that in Letters Patent X0. 1.5(i8,9l5, grantedJanuary 5, 1926, lrpon'the application of Lars H. Bergman, of Chicago,Illinois. for an improvement in Apparatus forPulverizing and FeedingFuel to Furnaces, an error appears in the printed specificationrequiring correction as follows: Page 4. line 46. claim 9, after theword mill insert the Words 11260118 for auzolnuf-iriaily ciosz'ng thevalve; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 2d day of February, A. D. 1926.

[SEAL.] VM. A. KINNAN, Acting Commissioner of Patents.

